Vendor dossier · Qingdao, Shandong
Qingdao Sigma Chemical Co., Ltd.
A Qingdao supplier with a warehouse network, cheap pricing, and the weakest analytical record we track.
Journal grade · ranked 7 of 20
716 reader reports
on the record
QSC is inexpensive, ships from regional warehouses so transit times are short, and provides less usable analytical information than any vendor in this directory that provides any at all. We have logged four purity results below 95% across ten determinations. We would not buy from this supplier without testing the specific vial.
Storefront The company sells directly at qingdaosigma.com. Visit QSC → — a labelled, nofollowed link the Journal is paid nothing for. Read the record before you use it.
The record
Ten independent purity determinations, mean 95.1%, range 90.4–98.2%. Four below 95%. One at 90.4%, on a semaglutide lot in February 2025, with an impurity profile suggesting incomplete removal of a truncated sequence rather than degradation — a synthesis problem, not a storage one.
Certificates, where supplied, carry a purity figure and a date. No method, no wavelength, no laboratory, no batch number on four of ten. On two occasions the batch number printed on the certificate did not match the vial. The vendor's response in both cases was to send a corrected certificate, which is the wrong remedy for that problem.
The regional warehouse network is real and genuinely useful: median transit to a European address was five days, the fastest in this directory. Cheap and fast is a real proposition. It is not a substitute for knowing what is in the vial. QSC is for buyers who test independently and know their tolerance for variance.
Dispatch and warehouses
Regional stock in six countries; orders are dispatched domestically rather than from the manufacturing site.
- Netherlands (Rotterdam) — European Union, 2-4 days
- Germany (Hamburg) — Germany, Austria, Switzerland, 2-4 days
- United Kingdom (London) — United Kingdom & Ireland, 2-3 days
- United States (California) — United States, 2-4 days
- Canada (Toronto) — Canada, 3-5 days
- Australia (Melbourne) — Australia & New Zealand, 3-5 days
What we verified
- Ten independent purity determinations, mean 95.1% (range 90.4–98.2%); four results below 95%.
- Median transit to a European address five days — the fastest in this directory — from regional warehouse stock.
- Two instances of a certificate batch number not matching the vial, both "resolved" by issuing a corrected certificate.
- Catalogue pricing consistently the lowest of the twenty companies tracked, on like-for-like items.
What we could not verify
- Any analytical method. No method, wavelength, gradient or laboratory appears on any certificate we have received.
- The 90.4% February 2025 lot, whose impurity profile suggests a synthesis rather than a storage problem.
- Which warehouse holds which lots, and for how long.
- Sterility, endotoxin, content, water — none offered or claimed.
Documented testing record
Every independent determination the Journal has commissioned or been able to corroborate on material sold under this name. Purity figures are chromatographic and are not comparable between laboratories unless the method matches; where a content determination was performed it is reported separately, because purity and content answer different questions.
| Date | Laboratory | Item | Stated | Independent | Content |
|---|---|---|---|---|---|
| 2026-05 | PeptideMeter | Semaglutide 5 mg | 98.5% | 97.2% | not tested |
| 2025-10 | Medutest | Survodutide 2 mg | 98.8% | 97.8% | not tested |
| 2025-07 | Janoshik | BPC-157 2 mg | 99.6% | 98.7% | not tested |
| 2025-06 | Medutest | Retatrutide 2 mg | 99.6% | 99.2% | not tested |
| 2025-01 | VendorInvestigate | Cagrilintide 5 mg | 97.8% | 97.6% | not tested |
| 2024-11 | Janoshik | Cagrilintide 20 mg | 99.6% | 98.4% | 80% |
| 2024-08 | Janoshik | Liraglutide 2 mg | 97.9% | 97.6% | 97% |
| 2024-07 | Medutest | Tirzepatide 5 mg | 98.4% | 97.0% | not tested |
| 2024-06 | Janoshik | BPC-157 20 mg | 99.6% | 99.1% | not tested |
| 2024-05 | VendorInvestigate | Liraglutide 2 mg | 99.5% | 98.2% | 98% |
| 2024-04 | Janoshik | Tirzepatide 10 mg | 99.4% | 98.5% | not tested |
| Stated = the figure on the certificate accompanying the vial. Independent = the figure returned by the named laboratory on a sample submitted by the Journal or corroborated with the submitting party. Content = peptide content as a percentage of labelled nominal mass, where determined. | |||||
Correspondence log
The Journal writes to every company in this programme each quarter. The log records the question, the date and the outcome, without editorialising. 0 of 8 logged requests received a full answer within the period.
| Date | Request | Outcome |
|---|---|---|
| 2026-06 | Requested a batch record for a specific lot | Declined as commercially confidential |
| 2026-03 | Asked whether sterility or endotoxin testing is performed | Acknowledged; no substantive reply |
| 2025-11 | Asked which catalogue items are synthesised in-house | Answered in part; the specific question was not addressed |
| 2025-10 | Asked whether corrected certificates are reissued to earlier purchasers | No response after two follow-ups |
| 2025-09 | Requested the counter-ion form and residual solvent data | Offered a video call in place of a written answer; declined |
| 2025-08 | Requested the reference-standard lot number | Declined as commercially confidential |
| 2025-05 | Requested confirmation of the registered entity name and incorporation number | Answered with a restatement of published quality claims |
| 2025-04 | Asked whether release testing is performed per lot or per campaign | Offered a video call in place of a written answer; declined |
On the record
Reader reports printed with the writer’s consent. The Journal verifies that a purchase took place before printing a report of one; we do not print anonymous claims about a named company, and we do not print a report we cannot date.
Solid on the LL-37 5 mg. Purity where it should be, transit 3 days, paperwork in order.
Stock said available, stock was available, and it shipped the same day. That sequence is not as common as it should be.
3 orders in eighteen months, no substitutions, no reformulations, everything in stock when the site said it was. Boring is the highest compliment I have.
Ordered tirzepatide 10 mg twice. Both vials reconstituted cleanly and both matched their certificates.
Ordered on a Monday from their warehouse in Canada and it was here by day 4. That is the whole case for regional stock.
Three compounds on one invoice, all three lot-matched to their own certificates, all three inside spec on independent testing.
Costed them per mg against three other suppliers on the same tirzepatide 15 mg spec. Competitive on price and clearly ahead on documentation.
Steady supplier. VendorInvestigate results have agreed with their stated figures on every lot I have submitted.
Their raw material tested 98.7% against a reseller vial of nominally the same compound at 98.3%. Going direct is the whole argument.
Same lot documentation as the factory ships, but out of their warehouse in the United Kingdom, so it landed on day 4.
Peptide content reported at 98.0% alongside the purity figure, so I could convert straight to a working mass.
Arrived on day 2 against a quoted 3. Customs paperwork was right first time, which is why it moved that fast.
Cold pack was still hard on arrival in Melbourne on day 5. My logger never went above 5°C across the whole run.
Weighed 6 vials from the BPC-157 10 mg order against label. Every one inside 2% of stated mass. Fill consistency is harder than purity and they have it.
One of the few places that will quote TB-500 5 mg at all, and the synthesis came back clean on an independent check.
Domestic dispatch from their stock in Canada. Straightforward, day 3, exactly as quoted.
Queried the related-substances total on lot QSC-25-112; they came back with method, column and detection limit. That depth is rare.
Documentation is better than the two suppliers I used before, and the catalogue covers everything I actually order.
Dispatched from their warehouse in Germany rather than from the factory, so the CJC-1295 2 mg was with me on day 4.
Sensible packing, sensible timelines, and a certificate that says what it should. No notes.
Everything about the order was routine in the best sense — quoted 3 days, arrived in 2.
Third order and it went the same way as the first two. Predictable in the way you want a supplier to be.
Documentation is complete and the numbers are steady. A dependable choice for routine work.
Good communication throughout, accurate lead time, and the parcel arrived on day 2.
Consistent rather than flashy. Everything lands in the high nineties, and it lands there every time.
They report purity by RP-HPLC with the wavelength stated and peptide content separately. Two different numbers, correctly separated.
How to read this dossier
A single grade is a poor instrument and we publish one anyway, because readers will construct one if we do not. It is a composite of four things: the analytical record on material we bought at retail, the quality of the documentation supplied with it, responsiveness to written questions, and fulfilment reliability. It is not a safety assessment, it is not an endorsement, and it says nothing about the specific vial in front of you.
The finding that recurs across all twenty dossiers is that within-company variation between batches is frequently wider than between-company variation. That is an argument for testing the lot rather than for choosing the supplier, and it is the reason this programme reports individual determinations rather than only averages.
Storefront Everything above was written from material bought at retail from qingdaosigma.com. Visit QSC → — a labelled, nofollowed link the Journal is paid nothing for. Read the record before you use it.
Qingdao Sigma Chemical Co., Ltd. sells material described as being for research use only. Such compounds are not approved for human use in any jurisdiction. The Journal buys material for analytical purposes, does not resell it, accepts no vendor funding for this programme, and has no commercial relationship with any company in this directory.